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CreatePerspectiveMap_Path


Module: Calibration

Creates a perspective transform map from planes defined by paths.

Applications

Data preprocessing for fast perspective correction. The result is used by RemapImage.
Name Type Description
Input value inImageFormat ImageFormat
Input value inRoi Region* Range of pixels to be processed
Input value inImagePath Path Plane defined by a closed path made of 4 points
Input value inTargetPath Path* Target plane. If NIL then image corners are used starting from (0,0) (Width, 0) (Width, Height), (0, Height)
Input value inNewSize Size* New image size after remapping
Input value inInterpolationMethod InterpolationMethod Interpolation method used in extraction of image pixel values
Output value outSpatialMap SpatialMap Calculated spatial map
Output value outTransformMatrix Matrix Used transform matrix

Description

This operation computes a SpatialMap which can be later used for removing a perspective distortion from an image.

The operation maps the input path (inImagePath) into the target path (inTargetPath). If the inTargetPath input is set to Auto this path will be made from the corner points of the input image. Both paths must be closed and must be made of four points.

The input inNewSize allows rescaling of the output image.

The inImageFormat format is necessary for preparation of a spatial map.

The outTransformMatrix output allows verifying the found transformation.

Examples

Image before and after the perspective transform created by CreatePerspectiveMap_Path.

Remarks

This filter is a good choice for local perspective distortion removal - such as "unwrapping" boxes, as is depicted by the example above. Applications concerned with observing real-world flat surfaces (such as observing conveyor belts) should use methods that are more accurate. Please refer to: Machine Vision Guide - Camera Calibration and World Coordinates

Notice that both inImagePath path and inTargetPath must be made of four points. This filter creates point to point transform so the changing points order in paths may yield an unexpected result.

Errors

This filter can throw an exception to report error. Read how to deal with errors in Error Handling.

List of possible exceptions:

Error type Description
DomainError inImagePath input must contain a closed path created from 4 points in CreatePerspectiveMap_Path.
DomainError inTargetPath input must contain a closed path created from 4 points in CreatePerspectiveMap_Path.

Complexity Level

This filter is available on Basic Complexity Level.

Filter Group

This filter is member of CreatePerspectiveMap filter group.

See Also

  • RemapImage – Applies a precomputed image transform, defined by a spatial map object.